Selective Colorimetric Detection of Cyanide and Fluoride from Carbazole Possessing Nitro-azobenzene

Abstract

A colorimetric sensor based on carbazole and nitro-azobenzene (1) was successfully synthesized and was able to selectively detect the strong basic anions which are F^- and CN^- by a “naked-eye” color change from light yellow to red in acetone media. This change in color corresponded to a red shift observation of the sensor absorption band after F^- and CN^- addition. Result from ¹H-NMR titration revealed a deprotonation of sensor 1 at NH-amide binding unit. A host-guest complex formation of 1:2 stoichiometry was calculated. A preliminary study in a detection limit of 1 for anion sensing using the naked eye observation was obtained the values of 4x10^-4 and 2x10^-4mol/L for F^- and CN^-, respectively.